Volume 40, Issue 5 (September 2012)
Chloride Binding Capacity of Cement Paste Containing Layered Double Hydroxide (LDH)
The chloride binding capacity of concrete can affect the rate of chloride ingress, which ultimately determines the chloride-ion resistance. A layered double hydroxide (LDH) can absorb the chloride ions in cement paste and delay chloride ingress in the structure. A method for evaluating the chloride binding capacity of cement paste was used in the experiment reported herein. We compare Mg-Al LDH under different treatments (including CO32− series and NO3− series) in order to determine the chloride binding capacity of the LDH. The binding mechanism is explored in this article. The experimental results indicate that LDH processes have a remarkable chloride ion binding capacity. The addition of LDH can improve the chloride binding capacity of cement paste significantly. Cement paste containing roasted LDH has a better chloride binding capacity than that containing unroasted LDH or rehydrated LDH. Based on the comparison of LDHs with different anions, the chloride binding capacity of NO3− series LDH appears to be more powerful than that of CO32− series LDH.